Php 404 Not Found Header

Question

I am trying to understand a combination of three simple lines of php code. This is the code:

ob_end_clean(); header('HTTP/1.0 404 Not Found'); exit; 

So, this is the code, and as I understand it, the first line is ob_end_clean (); . It can help, for example, using the specification (bytes). . So the first line is to prevent any previous exit.

The second header ('HTTP / 1.0 404 Not Found'); - heading.

And the third line exit completes the execution of the script.

If I delete the first line and I have the specification in the document, I get a blank page (No. 404).

If I delete the third line ( with and without specification ), I get a page on which I do not need a blank page, not 404.

• Mabye, if anyone can explain why I should use exit . 404
• Also why with the spec I don't get "headers have already sent an error"

Thank you all and have a nice day.

Answer 1

If I delete the first line and I have the specification in the document, I get a blank page (No. 404). you will get an empty 404 because you do not have the content defined there ...

 header('HTTP/1.0 404 Not Found'); 

only reports that the user is on the page of the 404 error page ... if you want to display a notification for the 404 user, you can do this by downloading the 404.html file

 if(strstr($_SERVER['REQUEST_URI'],'index.php')){ header('HTTP/1.0 404 Not Found'); readfile('404missing.html'); exit(); } 

or directly

 if (strstr($_SERVER['REQUEST_URI'],'index.php')){ header('HTTP/1.0 404 Not Found'); echo "<h1>Error 404 Not Found</h1>"; echo "The page that you have requested could not be found."; exit(); } 

Exit function

exists because you need to prevent the execution of other php code, which can be immediately after if or which can be deleted later, it just says END

Answer 2

Why should I use output After heading 404

Thus, no further code will be executed. If not, then in this case it is not necessary. It's a good habit to come in though.

Also why with BOM I do not get "headers already sent errors"

You have not configured your PHP installation to show end users errors and notifications.